Corrosion inhibiting and fingerprint



United CORROSION INHIBIT ING AND FHNGERPRINT REMOVING COMEOSITION N Drawing. Application May 23, 1952, Serial No. 289,654

19 Claims. Cl. 106-14) This invention relates to corrosion inhibiting compositions, and more particularly pertains to rust preventive compositions adapted to remove salt and acids which cause corrosion and to prevent and/ or inhibit salt-type corrosion, particularly fingerprint corrosion of metals.

Salt-type corrosion of metals is so named because corrosion of the metal is partially due to adherent inorganic salt particles, rather than to external fluid agencies. A particular form of salt-type corrosion is the so-called fingerprint corrosion which generally follows the handling of metal stocks and is in some way related to the acids and salt deposited on the metal or perspiration transferred from the hands of the handlers of such metal stocks. This salt-type or fingerprint corrosion is particularly diflicult to avoid or inhibit in spite of the fact that its general nature has been recognized by metal workers and others for many years. This type of corrosion problem has persisted in spite of extensive developments in the field of slushing compounds. Slushing compounds are rust reventives and are usually classified as liquid or oils or solid or greases from the standpoint of appearance, handling and service properties. Slushing compounds appear to exert a protective effect on metal surfaces in part by forming an adherent coating and in part by the effects which may be attributed to anti-rust agents, dissolved or dispersed in such composition. For reasons not clearly understood, it has been found that salt-type or fingerprint corrosion can continue under a protective coating of slushing compounds in numerous instances where the metal has been handled manually before the application of the slushing compound. The presence of a salt-type fingerprint corrosion can be to a large extent combatted by using corrosion inhibiting compositions having the properties of (1) readily displacing Water, (2) removing substantially all adherent corrosive substances, such as salts and acids present in human perspiration, and (3) suppressing or inhibiting further corrosive influences. To a large extent the problem of preventing and/ or removing fingerprint corrosion has been successfully accomplished by the use of slush ing compositions of the type described in copending application Serial No. 80,568 filed March 9, 1949 by Donald I. Walker and Edgar A. Dieman now U. S. 2,598,949 issued June 3, 1952. However, under certain conditions, for unknown reasons, completely satisfactory results are not always attained by the use of such compositions.

It is an object of the present invention to provide an improved composition for preventing and/or inhibiting corrosion of metals. Another object of the invention is to provide compositions especially adapted to displace Water and remove acids and salts in combatting corrosion of atent 2,796,353 7 Patented June 18, 1957 Percent Alkaline earth soaps of. preferentially oilsoluble sulfonic acids (100% soap) 3 to 15 F Hydrocarbon solvent 40 to 60 Water 1 to 10 Water-soluble oxygenated organic solvent 1.0 to Preferentially water-soluble sulfonates 0.5 to 7 Carbocyclic acid 0.1 to 5 Hydrocarbon oil 5 to sulfonation of olefin polymers having at least about 22 carbon atoms in a molecule or those obtained by the sulfonation of alkylated aromatics having at least about- 19 carbon atoms, can also be used.

Preferentially oil-soluble petroleum sulfonic acids are those obtained in the treatment of petroleum oils to obtain highly refined products of the type of technical insulating oils, turbine oils, medicinal white oils, technical white oils, etc., in which the petroleum oils are treated successively with a number of portions of concentrated sulfuric acid, i. e. above about 95% strength, or fuming sulfuric acid. A variety of sulfur-containing compounds are formed by chemical reaction of the sulfuric acid upon the oil, including sulfonic acids, organic esters of sulfuric acid, and partial esters of sulfuric acid. Most of these compounds are relatively insoluble in the oil under treating conditions and separate from the oil together with unreacted sulfuric acid as a sludge, which is separated from the oil after each treatment. The sulfuric acid is usually added in dumps of about one half pound per gallon of oil, the total quantity of acid added depending upon the oil being treated and the final product. Usually, from about three pounds to about nine pounds of sulfuric acid per gallon of oil are used. Some of the sulfonic acids resulting from the treatment of the oil with the sulfuric acid are preferentially oil-soluble and remain in the oil layer after removal of the acid sludge. The sulfonic acids in the acid-treated oil can be extracted therefrom with an alcohol of -70% strength, and the extracted sulfonic acids neutralized with a basic alkaline earth compound, such as for example, lime.

oil, there can be recovered from the acid sludge by suitmetals. Still another object of the invention is to provide SSS excellent properties for prevention and/or inhibitable solvents, preferentially oil-soluble sulfonates or sulfonic acids. The term preferentially oil-soluble sulfonates therefore includes the oil-soluble sulfonates recovered from the acid-treated oil and the acid sludge.

While any of the preferentially oil-soluble alkaline earth sulfonates, such as calcium, barium, or strontium sulfonates-can be used, we prefer to employ those obtained from the preferentially oil-soluble sulfonic acids. having combining molecular Weights in the range of from, about 350 to about 525, and preferably those in the range;

3 of from about 420 to about 500. The sulfonic acid soaps obtained in the manner described contain from about 30% to about 60% sulfonate, from about 30% to about 60% oil, up to about 2.0% water, and less than 0.5% inorganic salts.

The calcium soaps of the preferentially oil-soluble petroleum sulfoni acids or mahogany acids are preferred, and the preparation thereof is illustrated by the following example: A Mid-Continent petroleum distil late having a Saybolt Universal viscosity at 100 F. of between 220 seconds and 230 seconds, is treated with 6 pounds of fuming sulfuric acid per gallon of oil in onehalf pound dumps. After the separation of the acid sludge, the acid-treated oil is treated with a suitable alcoholic, for example, ethyl alcohol of about 6% strength to remove crude preferentially oil-soluble petroleum sulfonic acids. The alcoholic layer containing the crude sulfonic acids is then treated with lime, preferably in the form of a lime slurry to neutralize-the sulfonie acids. The mixture is allowed to settle, the alcohol layer containing the calcium mahogany soap is drawn off and then distilled to remove the alcohol therefrom. The resultant calcium soap of the preferentially oil-soluble petroleum sulfonic acids is usually of 70% to 80% concentration in unreacted oil. To facilitate the handling of the soap, it is preferred to further dilute the soap with a petroleum oil of suitable viscosity to a concentration of about The hydrocarbon oil content of the composition is that present in the petroleum sulfonate compound, and, if desired, added as additional oil. As noted above, the petroleum sulfonate product contains 6065% hydrocarbon oil of suitable viscosity. Usually oils of from about 50 to about 1000 seconds Saybolt Universal viscosity at 100 F are used.

The hydrocarbon solvent is one boiling in the range between about 100? F. and about 650 F. Hydrocarbon solvents which we have found suitable for the purposes herein described are preferably petroleum distillates, such as petroleum ether, gasoline, naphthas or kerosenes of the desired distillation range. Of the hydrocarbon oil fractions it is preferred to employ a solvent boiling in the gasoline to kerosene boiling range, and particularly good results are obtained by employing a heavy naphtha boiling in the range of between about 300 F. and 400 F. at atmospheric pressure, such as for example, the hydrocarbon solvent commonly known as Stoddards solvent. 7

In order to prepare clear, bright and stable compositions, and yet produce compositions especially adapted to penetrate and displace water on the surfaces of metals for the removal of corrosive substances thereon, we have found it necessary to employ as a mutual solvent for the water and oil, as well as an aid in fingerprint removal, a Water-soluble oxygenated organic solvent, particularly aliphatic alcohols and ketones. While We prefer to use alcohols and ketones boiling below about 180 F. at atmospheric pressure, alcohols and ketones of higher boiling points can be suitably employed. Examples of suitable water-soluble oxygenated organic solvents are isopropyl alcohol, propyl alcohol, ethyl alcohol, methyl alcohol, methylethyl ketone, as well as higher boiling alcohols, and ketones, for example, tertiary butyl alcohol, hexylene glycol, butyl carbitol, diacetone alcohol and the like.

The preferentially water-soluble sulfonates used in the herein-described composition is employed as a coupling or wetting agent and is suitably selected from a variety of compounds, including various sulfonated fish or animal oils, vegetable oils, fats and waxes, and preferentially water-soluble alkali metal soaps of petroleum sulfonic acids having molecular weights in the range of from about 400 to 430. The sulfonated fish, animal, vegetable oils, fats or waxes are rendered preferentially watersoluble by being partially or Wholly neutralized with a caustic solution, for example, sodium, potassium or ammonium hydroxide. Preferred coupling agents are a Water-soluble sulfonated castor oil prepared by adding to a sulfonated castor oil sufficient caustic solution to neutralize any residual or unreacted sulfuric acid and wholly or partially neutralizing the sulfonated fatty acid content, and alkali metal soaps of petroleum sulfonic acids of about 400 to 430 molecular weight and which are more water-soluble than the alkaline earth sulfonates used in the composition.

In addition to the foregoing, an essential component of the herein-described composition is a carbocyclic acid, illustrated by acids such as benzoic acid, cinnamic acid, naphthenhydroxamic acid, etc., which assists in the complete removal of residual salts deposited on the metal surfaces and which causes salt-type or fingerprint-type corrosion.

The following examples will serve to illustrate compositions of the present invention:

Example 1: Percent volume Preferentially oil-soluble calcium mahogany soap (1) 24.3 Stoddards solvent 56.7 Isopropyl alcohol 10.4 Water 5.6 Water-soluble sulfonated castor oil 0.5 Benzoic acid 2.5 Example II: Percent weight Preferentially oil-soluble calcium mahogany soap* (1) 22.9 Stoddards solvent 53.5 Isopropyl alcohol 9. 6 Water 6.7 Water-soluble sulfonated castor oil 0.5 Sodium mahogany soap** (2) 5.8 Benzoic acid 1.0

Example 111:

Preferentially oil-soluble calcium mahogany soap*=** 22.8 Sodium mahogany soap 4.9 Water-soluble sulfonated castor oil 0.5 Stoddards solvent 53.0 Isopropyl alcohol 10.9 Water 6.9 Benzoic acid 1.0 Example IV:

Preferentially oil-soluble calcium mahogany soap* 23.5 Sodium mahogany soap (2) 3.0 Stoddards solvent 55.0 Isopropyl alcohol 11.0 Water 7.0 Benzoic acid 0.5 Example V:

Preferentially oil-soluble calcium mahogany soap* 23.5 Sodium mahogany soap** 3.0 Water-soluble sulfonated castor oil 0.5

Stoddards solvent 55.0 Isopropyl alcohol 10.5 Water 7.0 Cinnamic acid 0.5

Example VI:

Preferentially oil-soluble calcium mahogany soap* 23.5 Paraflin oil 5.0 Sodium mahogany s0ap** 3.0 Stoddards solvent 58.0

Water 5.0

Butyl carbitol 5.0 Benzoic acid 0.5

. Footnotes stand of examples.

Example VIII: Percent volume Preferentially oil-soluble calcium mahogany soap* 23.5 Sodium mahogany soap** 3.0 Stoddards solvent 55.0 Dimethyl ketone 11.0 Water 7.0

BenZOic acid 0.5 Example IX: Percent weight Preferentially oil-soluble calcium mahogany soap* 30.0 Sodium mahogany soap** 2.0 Stoddards solvent 55.0 Diacetone alcohol 5.0 Water 5.0 Naphthenhydroxamic acid (50% in oil) 3.0

* Sulfonic acid molecular weight470.

sulfonic acid molecular weight-430, sodium soap more water-soluble than calcium mahogany soaps used in formulatwfst Sulfonic acid molecular weight500.

( 37% soap; 63% oil.

( 50% soap; 50% oil.

The alcohol in the foregoing examples may be substituted by ketones in the proper proportions.

The fingerprint removal property of the composition of the present invention was determined by subjecting various of the above examples to a fingerprint removal test carried out in the following manner: sand blasted and polished test panels of SAE-1020 steel were respectively spotted with drops of a synthetic fingerprint solution and dried for five minutes in an oven I31; 250 F. The synthetic fingerprint solution, having approximately the same corrosive effect on metals as human perspiration, is prepared by dissolving 7 grams of sodium chloride, one gram urea and four grams lactic acid in 50% methanol, and diluting the mixture to 250 cc. with additional 50% methanol. This solution is then diluted by the addition of 4.33 cc. of alcohol per cc. of solution before used.

The application of synthetic fingerprint solution was also accomplished by a slightly different technique in other tests. The synthetic fingerprint solution was prepared by dissolving 7 grams of sodium chloride, one gram urea and four grams lactic acid in equal parts of anhydrous methanol and water to make one liter of solution. One and one-half cc. of this solution was placed in the center of a 1 /2 x 1 /2 inch gauze pad 32 ply in thickness. A number 7 gum rubber stopper, roughened with 240 grit alundum paper and weighed with a one kilogram weight, was used to transfer synthetic fingerprint solution from the gauze pad to the cleaned test panel. This was followed by drying for five minutes at 250 F. We have found that the two methods of fingerprint solution application are substantially equal in severity; the former method involving a greater quantity of more dilute solution and the latter method involving a lesser quantity of more concentrated solution.

The dried, treated steel test panels were removed from the drying oven, cooled to room temperature and slushed with several of the above-described compositions. The slushed steel test panels were then rinsed with naphtha and then dried. The dried, treated test panels Were then immersed in molten petrolatum which is known to have substantially no fingerprint rust preventive qualities, and after cooling suspended in a humidity test cabinet for five days to determine the extent of rusting, if any. At the end of the five-day period the petrolatum is washed off the test panels, and if no corrosion is evident where the syn-.

thetic fingerprint solution was applied the removal thereof is considered complete. If the removal of the synthetic fingerprint solution was not complete, rusting or corrosion is noted where such solution was deposited.

Steel test panels treated with the synthetic fingerprint solution, slushed with Examples I, II, III, IV, V, VI, VII and IX and then subjected to the above-described test, showed no evidence of corrosion; demonstrating the efiectiveness of such compositions in removing fingerprints.

The rust inhibiting property of the herein-described compositions was determined by subjecting steel test panels slushed with a composition of the present invention. to a humidity cabinet test.

In the humidity test, slushed steel panels are suspended in a special cabinet described in the National Military. Establishment specification designated JAN-H-792 (6/21/49), andthe time of initial corrosion of the panels. noted. The humidity cabinet is provided with heating units and thermal regulators for automatic temperature. control, and a water level is maintained in the bottom of the cabinet to give approximately humidity at all times. The steel panels are coated by dipping into the rust preventive material and are suspended in the cabinet by stainless steel or Monel hooks. The JAN-H492 specification is modified to the extent that a temperature of 100 F. (:2" F.) instead of F. (i2 F.) is maintained in the cabinet, and from 1 to 1.5 complete changes of saturated air per hour are provided in the cabinet, instead of 8(1t1) linear feet per hour.

Test panels treated with the composition of Example IV passed over 500 hours in the humidity cabinet without showing evidence of rusting.

Unless otherwise stated, percentages given herein and in the appended claims are weight percentages.

While the present invention has been described by reference to specific embodiments thereof, these are given by way of illustration only and the invention is not to be limited thereto but includes within its scope such modifications and variations as come within the spirit of the appended claims. 7

We claim:

1. A composition of matter consisting essentially of from about 3% to about 15% of a preferentially oil-soluble alkaline earth sulfonate, from about 40% to about 60% of a hydrocarbon solvent boiling in the range of from about 100 F. to about 650 F., from about 1% to about 15 of a water-soluble oxygenated organic solvent selected from the class consisting of an aliphatic alcohol and an aliphatic ketone, from about 0.5% to about 7% of a preferentially water-soluble sulfonate, from about 0.1% to about 5% of a mono-basic carbocyclic acid selected from the class consisting of benzoic acid, cinnamic acid and naphthene hydroxamic acid, from about 1% to about 10% water, and from about 5% to about 20% of a hydrocarbon oil.

2. A composition as described in claim 1, in which the preferentially oil-soluble alkaline earth sulfonate is an alkaline earth soap of preferentially oil-soluble petroleum sulfonic acids.

3. A composition as described in claim 1, in which the preferentially oil-soluble sulfonate is a calcium soap of preferentially oil-soluble petroleum sulfonic acids.

4. A composition as described in claim 1, wherein the preferentially water-soluble sulfonate is a preferentially water-soluble alkali metal soap of petroleum sulfonic acids.

5. A composition as described in claim 1, wherein the preferentially water-soluble sulfonate is a water-soluble sulfonated castor oil.

6. A composition as described in claim 1, wherein the water-soluble oxygenated organic solvent is a Watersoluble aliphatic alcohol boiling below about 180 F.

7. A composition as described in claim 1, wherein the water-soluble ox enated organic solvent is i'sopropyl alcohol.

8. A composition of matter described in claim 1, Wherein the water-soluble oxygenated Organic solvent is an aliphatic ketone boiling below about 180 F.

9. A composition of matter describ'e'dincl'aim 1, wherein the water-soluble oxygenated organic solvent is butyl carbitol. I

10. A composition of matter described in claim 1 wherein the water-soluble oxygenated organic solvent is hexylene glycol.

11. A composition of matter described in claim 1, wherein the water-soluble oxygenated organic solvent is diacetone alcohol.

12. A composition of matter described in claim 1, wherein the ca'rbocyclic acid is benzoic acid.

' 13. A composition of matter described in claim 1, wherein the carbocyclic acid is cinnamic acid.

14. A composition of matter as described in claim 1, wherein the carbocyclic acid is napthenhydroxamic acid.

15. A composition of matter consisting essentially of from about 3% to about 15% of a calcium soap of preferentially oil-soluble petroleum sulfonic acids, from about 40% to about 60% of a hydrocarbon solvent having a distillation range of from about 300F. to about'400 F., from about 1% to about 15% of an aliphatic alcohol boiling below about 180 F., from about 0.5% to about 7% of a preferentially water-soluble sodium petroleum sulfonate, from about 0.1% to about 5% benzoic acid, from about 1% to about water, and from about 7% to about of a hydrocarbon oil.

16. A composition of matter consisting essentially of the following ingredients in approximately the following proportions, by volume:

17. composition of matter consisting essentially of the following ingredients in the following approximate proportions, by weight:

Percent blend-(37% soap, 63%-oil) 22.9 Stoddards solvent 53.5

Isopropyl alcohol. 9.6 Water 6.7 Water-soluble sulfonated 'castor oil 0.5 Preferentially watensoluble sodium mahogany soap blend soap, 50% oil) Benzoic acid 1.0

fonic acid soap (50% soap, 50% oil) 3.0 Stoddards solvent 55.0

lsopropyl alcohol 11.0 \Vater 7.0

Benzoic acid a 2 0.5

19. A composition of matter consisting essentially of the following ingredients in the following approximate proportions, by weight:

Percent Preferentially oil-soluble calcium mahogany soap blend (37% soap, 63% oil) 30.0

Sodium mahogany soap blend (50% soap, 50%

oil) 2.0 Stoddards solvent 55.0 Diacetone alcohol 5.0

Water 5.0 Naphthenhydroxamic acid 3.0

References Cited in the file of this patent UNITED STATES PATENTS 2,435,655 Rhodes et a1 Feb. 10, 1948 2,509,786 Schiermeyer et al May 30, 1950 2,598,949 Walker et al. June 3, 1952 2,610,151 Putman et al Sept. 9, 1952 2,615,815 Galuin Oct. 28, 1952 2,629,693 Barton et al Feb. 24, 1953 

1. A COMPOSITION OF MATTER CONSISTING ESSENTIALLY OF FROM ABOUT 3% TO ABOUT 15% OF A PREFERENTIALLY OIL-SOLUBLE ALKALINE EARTH SULFONATE, FROMABOUT 40% TO ABOUT 60% OF A HYDROCARBON SOLVENT BOILING IN THE RANGE OF FROM ABOUT 100*F. TO ABOUT 650*F., FROM ABOUT 1% TO ABOUT 15% OF A WATER-SOLUBLE OXYGENATED ORGANIC SOLVENT SELECTED FROM THE CLASS CONSISTING OF ANA LIPHATIC ALCOHOL AND AN ALIPHATIC KETONE, FROM ABOUT 0.5% TO ABOUT 7% OF A PREFERENTIALLY WATER-SOLUBLE SULFONATE, FROM ABOUT 0.1% TO ABOUT 5% OF A MONO-BASIC CARBOCYCLIC ACID SELECTED FROM THE CLASS CONSISTING OF BENZOIC ACID, CINAMIC ACID AND NAPHTHENE HYDROXAMIC ACID, FROM ABOUT 1% TO ABOUT 10% WATER, AND FROM ABOUT 5% TO ABOUT 20% OF A HYDROCARBON OIL. 